Question

Im working right now on a program that can divide, add, ect, but, im also making it for others, so, the problems usually have letters as well. What code could I implement so that my program ignores characters, and just focuses on numbers?

import static java.lang.System.out;
import java.util.Scanner;

public class Trinomial {
    public static void main(final String args[]) {
        final Scanner first = new Scanner(System.in);
        out.print("Enter the first number: ");
        final int First = first.nextInt();

        final Scanner second = new Scanner(System.in);
        out.print("Enter the second number: ");
        final int Second = second.nextInt();

        final Scanner third = new Scanner(System.in);
        out.print("Enter the third number: ");
        final int Third = third.nextInt();

        numFactors(First);
    }
}

Answer 1

Firstly, you will have to use next() method from the scanner, as nextInt() will return an exception if the next token contains non-digit characters. This will read the token as a String. Then you can get rid of non-digit characters by, for example, creating an empty String (for performance reasons StringBuilder can be better, but that makes it more complex), looping through the original string and using the already mentioned isDigit() method to determine whether the character is a digit. If it is, add it to your new string. Once you have a string containing only digits, use Integer.parseInt(string) method to get the integer value.

I am not quite sure, why you initialise a new Scanner every time, I think you should be able to use the first one throughout your program.